Tinnitus, a common auditory disorder, is most commonly known as “ringing of the ears” but is generally the perception of any type of sound in the absence of an external source of sound. Worldwide, tinnitus has been estimated to affect 10-15% of the population. Recent studies estimate the prevalence of tinnitus in the United States at 25.3%, affecting an estimated 50 million Americans (Shargorodsky et al., 2010). There currently is no cure, nor is there a standardized method to characterize tinnitus. Despite early attempts to characterize tinnitus dating back to the early 1900s (Snow, 2004) and a formalized call by the CIBA foundation in 1981 to develop general guidelines for the clinical assessment of tinnitus (Evered and Lawrenson, 1981), clinical tinnitus matching procedures have yet to be standardized and universally adopted in the current day (Henry and Meikle, 2000; Tyler, 2000; Henry et al., 2001; 2004). Although efforts have been made to find neural correlates of tinnitus, an objective measure of tinnitus does not yet exist (Miihlnickel et al., 1998; Diesch et al., 2010; Zeng et al., 2011a). Hence most current strategies focus on psychophysical methods. This is a critical procedure as the first step after a patient presents to a clinic with tinnitus is a medical evaluation from an otolaryngologist and audiologic assessment from an audiologist.
Yet there exists much room for improvement in psychophysical characterization of a patient's tinnitus percept. A paramount challenge of tinnitus matching is the sheer heterogeneity of the tinnitus percept experienced by tinnitus patients. Nearly half (46%) of patients have complex tinnitus consisting of more than one type of sound (Meikle et al., 1995). A questionnaire study characterizing tinnitus asked 528 patients to identify the sound quality most descriptive of their tinnitus. Common descriptors included ringing (38%), buzzing (11%), crickets (9%), along with hissing (8%), whistling (7%), humming (5%), and more (Stouffer and Tyler, 1990). It is against this observation of the heterogeneity of the tinnitus percept that the apparatuses and methods for matching tinnitus described herein were developed.